1. Field of the Invention
This invention relates to techniques for maintaining the hard quality of service (QoS) of the developing Internet. In particular, it relates to a method and system for controlling the admissible ingress and egress traffic of edge routers of the Multiprotocol Label Switching (MPLS) core network for achieving a non-blocking Internet backbone network.
2. Description of Related Art
Internet Protocol (IP) networks are traditionally designed to support a best-effort service, with no guarantees on the reliability and the timely delivery of the packets. As IP networks mature and are increasingly been used to support real-time applications, such as voice onto IP-based platforms, the existing IP networks need to provide a new level of QoS for such new applications. Differentiated Services (DiffServ) and MPLS have become the main QoS architecture for the Internet. DiffServ avoids per-flow bandwidth reservation inside the network. It classifies flows into aggregates (classes), and provides appropriate QoS for the aggregates. A small bit-pattern in each packet—the ToS octet of Ipv4 or the Traffic Class octet of Ipv6—is used to mark a packet for receiving a particular forwarding treatment at each network node. A service level agreement (SLA), is signed between a service providers and customers to specify the type of services and the amount of traffic required for each type. An SLA codifies what a provider promises to deliver in terms of what, how, and associated penalties for failures.
QoS requirements of SLAs need to be achieved with components in both the data-plane and the control-plane. Data-plane components include traffic shaping and policing, traffic classification, scheduling and buffer management. Control-plane components include SLA creation and configuration, signaling and SLA admission control (SAC) and network provisioning/traffic engineering. Effective implementations of data-plane components are well understood and available; only local state information in a router or switch is required. In contrast, control-plane components, such as SAC and network dimensioning, remain open issues. The challenges of the control-plane design arise from the fact that the implementations of control-plane components need the state information of the entire network. Typically there are millions of flows traveling through a high-speed link, and therefore maintaining the state information of all links of the entire network is simply not practical.
There are several proposals for SAC. The general concerns about these proposals include the following.
(a) Scalability and Effectiveness: referring to FIG. 1, the network equipment that performs provisioning, resource management and SAC is called bandwidth broker (BB). BB architecture implies that admission control decisions are made at a central location for each administrative domain, such as ISP A 101 and ISP B 105. Although the cost of handling service requests is significantly reduced, it is unlikely that this approach can be scaled upward for large networks. In order to cope with scalability, most relevant studies adopt distributed admission control schemes, which are further distinguished into model-based and measurement-based approaches. Both approaches assess QoS deterioration probability upon service request arrivals; model based approaches maintain state information for active services and employ mathematical models, whereas measurement-based approaches rely on either passive or active aggregate measurements. The main concern is the effectiveness of the schemes. The centralized SAC, although not scalable, can provide better QoS than the distributed admission control scheme.
(b) Applicability y to Inter-domain QoS All SAC schemes must fully address the inter-domain QoS issues. It is anticipated that there will be significant variation in the implementations and resource management strategies from one ISP to another. It is unlikely that we will find a unified approach across the Internet. Cascading different QoS approaches will work only if they cooperate with each other. That is difficult to achieve. For example, if one network uses measurement-based SAC and the other uses model-based SAC, it is unlikely that the end-to-end QoS can be achieved as anticipated for an SLA path passing through the two networks
While some QoS capabilities based on isolating voice traffic over IP are currently evolving (e.g., DiffServ, MPLS), providing end-to-end QoS at a large scale and across domain boundaries remains a challenging and unsolved problem. Thus a need exists for designing a new and practical SAC scheme to maintain the QoS in the future Internet.